Purple dots on screen

Plasma screens are extremely susceptible to getting broken from any impacts to the face of the screen. What you are describing sound very much like distorted or dead pixels. It may not be a fixable issue, you may have to replace the entire unit or live with the purple bar. The reason you don't notice it as much when the screen is dark is because purple is on the darker end of the spectrum, and will be most visible in contrast to lighter ad brighter colors.

Check the site linked below, and see the screen shots of defective LCD TVs, Surf it with patience. This should be a panel fault I assumes. http://electronicshelponline.blogspot.com/

From your description the seal in the lens housing has broken down, I would have it assessed by a professional to see if it can be salvaged.

My first guess is contamination on the lens or the internal LCD itself.
I would clean the lens first, and if that doesn't solve the issue, open the unit and clean the LCD panel.

This would have to be some sort of defect on the motherboard as long as these dots are only noticed when you turn on your console and not noticed while watching tv.

Just go to the service center where you bought that tv ,cause its ,one year warranty period. just consult your tv to the costomer service personel.

well u have stopped ur movies(dvds) to many times and the dots are burn marks on ur screens
if u read ur manual it will tell u NOT to leave a still picture on for to long as it will damage ur screen
i assume u have a PLASMA TELEVISION
if not... sorry cant help u

If lcd set the issue may be with the T con board which is responsible for video and any aberrations that you see on screen.

need to degause device to fix that color